Professional and amateur musicians often employ stringed instruments that are fitted with pickups, i.e., devices that allow the instruments to be electrically connected to an amplifier. However, the use of electric amplifiers and other peripheral equipment, such as microphones, creates a risk of electrical shock, which in some cases may be lethal.
The threat of electrical shock may arise through various types of electrical malfunction such as: 1) an electrical failure in the musician's equipment; 2) improper wiring of the power circuit to which the musician's equipment is attached; and/or 3) an electrical failure of peripheral equipment. One example of the first type of malfunction occurs when a guitarist's amplifier induces a high voltage to the ground side of the guitar output jack. An example of the second type of malfunction is improper wiring of a three-pronged electrical wall socket such as where the “earth” ground is not connected and the “neutral” and “hot” sides of the outlet are reversed, thereby resulting in a high voltage being applied to the “neutral” lead. An example of the third type of malfunction occurs when the musician's equipment is functioning properly while connected to properly wired wall sockets, but other equipment, such as a microphone, is improperly grounded.
Often in electric instruments, an earth ground is provided, such as through an amplifier. The earth ground reduces the amount of audible noise by providing a pathway for any induced noise to drain from the instruments circuitry. However, in some cases the earth ground is not present or is insufficient. A common way to provide noise reduction in instruments where the earth ground is lacking has been to provide the “grounded effect” by including a “string” ground.
String grounds are commonly used in electric guitar circuitry. A string ground generally includes a conductive path between the strings to the ground output or ground plane of the guitar circuitry. In the most common string ground configuration, the metal guitar strings touch a metal bridge and a wire that is connected between the metal bridge and the outside casing of a volume potentiometer or shielding inside the guitar. Although such a design provides a reduction in noise it also creates the mechanism, which in conjunction with any one of the previously mentioned malfunctions, may result in the musician being electrically shocked.
Suggestions for minimizing the risk of electrical shock have included checking the power outlets to which all of the musician's equipment, as well as any peripheral equipment, is connected with an outlet tester. However, such a practice may not always be feasible. Testing every outlet may be extremely time consuming and it may not be allowed where the sockets are used to power equipment not controlled by the musician.
The use of Ground Fault Circuit Interruptor (GFCI) extension cords has also been suggested as a practice that can reduce the risk of electrical shock. The practice includes plugging electrical equipment into a GFCI extension cord and plugging the extension cord into a wall socket. Such a circuit will trip, or open, if a certain threshold leakage current is detected. However, such a practice has various disadvantages. First, any GFCI extension cord must be tested prior to each use to assure that it is functioning properly. Next, a large number of the devices may be required for productions utilizing many pieces of equipment, which may result in the technique being prohibitively expensive. Additionally, to thoroughly utilize the technique a GFCI device must be used with any equipment that the musician will contact, including peripheral equipment not owned by the musician.
Various alterations to electrical musical instrument, such as guitars, have also been suggested to reduce the risk of electrical shock. For example, removing the string ground has been recommended. However, such an alteration also removes the noise reduction benefits provided by the ground.
Another suggested alteration requires placing a capacitor and a resistor in parallel within the string ground path. However, the alteration does not prevent a shock from occurring, but it may, if the capacitance and resistance are sufficient, prevent the shock from being lethal. In fact, the alteration does not provide a strict maximum current limit, but rather reduces the current level. As a result, even after the current has been reduced by such a device, the reduced current may still be lethal.
In view of the above, there exists a need for a musical instrument featuring a string ground path that is configured to reduce the risk of electrical shock.